Page 1 dataguard. ppt As of: 19-Feb-03 Oracle9i Data Guard Darl Kuhn Sun Microsystems RMOUG Training...

Page 1dataguard.ppt As of: 19-Feb-03

Oracle9i Data GuardOracle9i Data GuardOracle9i Data GuardOracle9i Data Guard

Darl Kuhn

Sun Microsystems

RMOUG Training Days 2003


Oracle9i Data Guard AgendaOracle9i Data Guard AgendaOracle9i Data Guard AgendaOracle9i Data Guard Agenda

• Business Requirements• What is Data Guard?• Data Guard Architecture• Implementing Data Guard• Failover when Disaster Strikes• 8i Data Guard New Features• 9i Data Guard New Features


Business RequirementsBusiness RequirementsBusiness RequirementsBusiness Requirements

Business Goals:• Keep the data 7x24 highly available• High Availability

– Minimize unscheduled downtime– Minimize scheduled downtime

• Disaster Recovery protection• Minimize Cost



Minimize Costs:• Hardware• Personnel (DBA, SA, etc.)• Special skills• Training• Licensing• Implementation• Maintenance



Minimize Complexity:• Number of moving parts

– Ease of implementation – Ease of maintenance

• More complex usually means more cost• Higher availability usually means more cost

Choose a solution that:• Meets business requirements• Minimizes cost and complexity


Business Solutions AvailableBusiness Solutions AvailableBusiness Solutions AvailableBusiness Solutions Available

• Backup the database, restore from tape• Operating System failover• Remote Mirroring• Quest Software SharePlex• Oracle Advanced Replication (OAR)• Oracle Real Application Clusters (RAC)• Oracle Data Guard (Standby)


We Chose Data GuardWe Chose Data GuardWe Chose Data GuardWe Chose Data Guard

• Needed 7x24 Disaster Recovery protection• Simple to implement• Requires DBA with B&R skills• Didn’t need special SA skills or consultants• Low maintenance (do more w/less DBAs)• We don’t have to baby-sit it• No extra licensing (built into Oracle9i)• Not an add-on, part of Enterprise Edition• Main cost was extra hardware


Data Guard HistoryData Guard HistoryData Guard HistoryData Guard History

• Previously known as the Standby Option• First developed by Oracle Consulting in the

late 80s early 90s• Became part of Oracle database in 7.3• Renamed to Oracle Data Guard in 8.1.7• Greatly enhanced in Oracle9i


What is Data Guard?What is Data Guard?What is Data Guard?What is Data Guard?

Built upon a simple concept:

1. Take a backup of your database

2. Move backup files to standby box

3. Mount standby database in recovery mode

4. Apply archived redo to standby database as

it becomes available from primary database


Copy and Apply Archive RedoCopy and Apply Archive RedoCopy and Apply Archive RedoCopy and Apply Archive Redo

• Oracle 7.3– Copy and apply of archive redo was manual

• Oracle8i– Automated copy and apply of archived redo

↪Uses ARCn and Net8 for copy↪Configured via init.ora parameters

• Oracle9i– Advanced archive gap detection– Uses Fetch Archive Log (FAL) process


Basic Physical Standby ArchitectureBasic Physical Standby ArchitectureBasic Physical Standby ArchitectureBasic Physical Standby Architecture

(picture for managers)

PrimaryDatabase

Primary DatabaseSite (production hardware)

LocalArchiveRedo

ARCn

Standby DatabaseSite (standby box)

(archived transactionsin an OS file)Damn

Users

StandbyDatabase

CopiedArchiveRedo

ManagedRecoveryProcess

Network

(a backgroundprocess)

Network


Basic Physical Standby ArchitectureBasic Physical Standby ArchitectureBasic Physical Standby ArchitectureBasic Physical Standby Architecture

.

PrimaryDatabase

Primary DatabaseProduction Site

LocalArchiveRedo

ARCn

Standby DatabaseServer

Users

StandbyDatabase

CopiedArchiveRedo

ManagedRecovery

Process (MRP)

LGWR

On-lineRedoOnlineRedo

Remote FileServer (RFS)

Fetch ArchiveLog (FAL)

OracleNet

CopiedArchiveRedo

LocalArchiveRedo


Implementing Data Guard in 10 StepsImplementing Data Guard in 10 StepsImplementing Data Guard in 10 StepsImplementing Data Guard in 10 Steps

Assumptions• Two different servers• Identical mount points on both boxes• Both primary and standby will have same name• Using ARCn process in this example (not LGWR)• http://otn.oracle.com/oramag/oracle/02-nov/o62avail.html

1. Ensure primary database is in archive log mode

2. Take backup of primary database datafilesSQL> select * from v$datafile;• Cold (easiest)• Hot• RMAN• Do not backup controlfiles• Do not backup on-line redo logs


Implementation (continued)Implementation (continued)Implementation (continued)Implementation (continued)

3. Copy backup datafiles to standby server• If you use an online backup, ensure that you copy over any

archive redo generated during the backup

4. Create a standby controlfile

SQL> alter database create standby controlfile as ‘stbycf.ctl’;

• This controlfile will be used by the standby database

5. Copy the standby controlfile to the standby box



6. Configure primary init.ora or spfile

# location of primary archive redolog_archive_dest_1=‘LOCATION=/ora01/oradata/BRDSTN/’

# location of archive redo on standbylog_archive_dest_2=‘SERVICE=standby1 optional’log_archive_dest_state_2=enable

7. Copy primary database init.ora file to standby box and make modifications for standby database

# Ensure standby database is pointing at standby controlfilecontrol_files=‘/ora01/oradata/BRDSTN/stbycf.ctl’

# Location of where archive redo logs are being written in standby environmentstandby_archive_dest=/ora01/oradata/BRDSTN

# Enable archive gap managementfal_client=standby1fal_server=primary1



8. Configure Oracle Net

• Need Oracle Net connectivity from Primary to Standby

and• Need Oracle Net connectivity from Standby to Primary• Primary database needs:

– Listener– TNS entry for standby1 service

• Standby database needs:– Listener– TNS entry for primary1 service


TNS FileTNS FileTNS FileTNS File

primary1 =

(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)

(PORT=1521) (HOST=primary_host))

(CONNECT_DATA=(SERVICE_NAME=BRDSTN)))

standby1 =

(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)

(PORT=1521) (HOST=standby_host))

(CONNECT_DATA=(SERVICE_NAME=BRDSTN)))



9. Startup and mount standby database

SQL> startup nomount;

SQL> alter database mount standby database;

10. Enable managed-recovery mode on standby

SQL> alter database recover managed standby database

disconnect;


Troubleshooting ImplementationTroubleshooting ImplementationTroubleshooting ImplementationTroubleshooting Implementation

• Continuously view bottom of primary and

standby alert.log files

$ tail –f alert_BRDSTN.log

• Most of problems are with getting Oracle Net

setup correctly (fat fingering a TNS entry)


When Disaster StrikesWhen Disaster StrikesWhen Disaster StrikesWhen Disaster Strikes

• Ensure you apply all applicable redo to

standby• Make the standby the primary• On standby

8i example:

SQL> shutdown immediate;

SQL> alter database mount standby database;

SQL> alter database activate standby database;

9i many more options:

SQL> alter database recover managed standby database finish;


When Disaster StrikesWhen Disaster StrikesWhen Disaster StrikesWhen Disaster Strikes

• Applications must change TNS to point to new

database• Or change Oracle Names entry• Or use Oracle Net load balance feature

brdstn=

(DESCRIPTION =

(LOAD_BALANCE=on)

(ADDRESS=(PROTOCOL=tcp)(HOST=l3srv1)(PORT=1521))

(ADDRESS=(PROTOCOL=tcp)(HOST=l3srv2)(PORT=1521))

(CONNECT_DATA=(SERVICE_NAME=brdstn))

)


When Disaster StrikesWhen Disaster Strikes

• Java Thin Driver Example

String connectInfo =

"jdbc:oracle:thin:@" +

"(DESCRIPTION =" +

"(LOAD_BALANCE=on)" +

"(ADDRESS=(PROTOCOL=tcp)(HOST=l3srv1)(PORT=1521))" +

"(ADDRESS=(PROTOCOL=tcp)(HOST=l3srv2)(PORT=1521))" +

"(CONNECT_DATA=(SERVICE_NAME=brdstn))" +

")";


Data Guard 8i New FeaturesData Guard 8i New FeaturesData Guard 8i New FeaturesData Guard 8i New Features

• Auto copy of redo to standby– Net8– Initialization parameters

• Auto apply of redo on standby• Enabled in standby database via

SQL> alter database recover managed standby database;



Read Only Mode:• Standby was mainly a disaster recovery and

high availability solution• Some limited scalability features• Can now open database in read-only mode

SQL> alter database open read only;

• And then back to recovery mode

SQL> alter database close;SQL> alter database recover managed standby database;



• Read Only mode allows for SELECT

statements to run against standby database• No DDL allowed in read-only mode• Applying of archive redo and read-only mode

mutually exclusive• Can either be in read-only mode or recovery

mode, but not both



• Archive gap management• Advanced data protection modes• Automated propagation of datafile operations• User error protection• Database switchover/switchback• Cascading standby• Archive_lag_target parameter• Logical Standby (version 9.2 only)• Data Guard Broker


Archive Gap ManagementArchive Gap ManagementArchive Gap ManagementArchive Gap Management

• What if network is down?• What if standby is down?• Primary continues to generate archive redo• Those unapplied redo logs make up an archive

gap• When failure is resolved how is the standby

caught up?



• In version 8, DBA has to figure out which

archive redo logs make up the archive gap• Copy over archive redo logs• Issue recover command on standby

SQL> alter database recover standby database;

• Then automatic ship and apply can restart



• Gap detection crucial to high availability• 9i has new methods for gap resolution• FAL_CLIENT and FAL_SERVER initialization

parameters initiate Fetch Archive Log (FAL)

processes• If network or standby is down• FAL process waits until communication is re-

established• Detects gap• Transmits and applies archive redo log


Data Protection ModesData Protection ModesData Protection ModesData Protection Modes

• Maximum protection– Guaranteed no-data-loss– Uses LGWR to transfer redo SQL> alter system set log_archive_dest_2=‘SERVICE=standby1 LGWR SYNC AFFIRM’;

– Standby configured with its own redo logs SQL> alter database add standby logfile (‘/ora01/oradata/BRDSTN/sb_redo_01.log’) size

10m;

• Maximum availability– Uses LGWR– Allows for temporary unavailability of standby

• Maximum performance– Default mode– Uses either ARCn or LGWR for transferring redo


Maximum Protection ArchitectureMaximum Protection ArchitectureMaximum Protection ArchitectureMaximum Protection Architecture

.

PrimaryDatabase


LocalArchiveRedo

ARCn

Standby DatabaseServer

Users

StandbyDatabase

ArchiveRedo

ManagedRecoveryProcess

LGWR

On-lineRedo

OnlineRedo

Remote FileServer (RFS)

OracleNet

StandbyOnlineRedo

ARCn

Synch/Asynchwrites

LocalArchiveRedo

ArchiveRedo


Propagation of Datafile OperationsPropagation of Datafile OperationsPropagation of Datafile OperationsPropagation of Datafile Operations

• Physical standbys have always supported all

data types• Supported all insert/update/delete statements• Supported most DDL

– Create table/view/index/sequence– Create user– Create package/procedure/function/trigger– Create role/synonym– Grants– Etc.



• One weakness of 8i was that add/drop

tablespace/datafile commands were not

automatically propagated• DBA had to intervene• Now automated in 9i• In standby initialization file

standby_file_management = auto



Example:

SQL> drop tablespace SHOLAY including contents and datafiles;

• On standby the tablespace SHOLAY will be

automatically dropped and all datafiles will

automatically be deleted from disk

• Note: If you want to rename a datafile, and

have those changes applied to standby, DBA

must intervene


User Error ProtectionUser Error ProtectionUser Error ProtectionUser Error Protection

• In 8i, DBAs often implemented a manual delay

in application of redo• Create a shell script that

– Copy archive redo– Wait 60 minutes before applying

• Idea being that if user accidentally

dropped/deleted/truncated data, the DBA could

intervene before it was applied to standby


User Error ProtectionUser Error ProtectionUser Error ProtectionUser Error Protection

• 9i you get more robust methods to manage

user errors• On standbySQL> recover managed standby database delay 60 disconnect;

• Archive redo copied to standby when

generated but not applied until 60 minutes

later• Disable the delay viaSQL> recover managed standby database nodelay;


Database SwitchoverDatabase SwitchoverDatabase SwitchoverDatabase Switchover

• Database can be in one of two roles• Primary or standby

SQL> select database_role from v$database;

• A switchover allows you to reverse roles of

primary and standby


Database SwitchoverDatabase SwitchoverDatabase SwitchoverDatabase Switchover

• Database switchover is not a database failover• A failover is permanently making a standby

database the primary database• Database switchovers would be ideal for

rolling OS upgrades• Switchovers cannot be used for database

upgrades


Cascading Redo LogsCascading Redo LogsCascading Redo LogsCascading Redo Logs

• Version 9.2 only• Standby can receive redo from another

standby• Reduce load on primary• Can receive redo from a physical or logical

standby• Setup standby redo log files• Ensure archiving enabled on physical standby


Archive_lag_targetArchive_lag_targetArchive_lag_targetArchive_lag_target

• Use archive_lag_target init parameter to

ensure online redo is switching often enough• Specifies in seconds how often you want an

online redo log switch to occur• Value in seconds• Valid values 0, or 60 through 7200• A value of 0 (default) disables this feature• 1800 (30 minutes) seems reasonable


Logical StandbyLogical StandbyLogical StandbyLogical Standby

• Prior to 9.2 you could only have a physical standby• Primary and physical identical down to the block level• With 9.2 you can now create a logical standby with the

Data Guard SQL Apply tool• Logical standby is available for SELECT access while

applying transactions from the primary via SQL

statements generated using LogMiner technology• Ideal for 7x24 reporting databases• Logical updates one or more log files behind the

primary


Logical Standby ArchitectureLogical Standby ArchitectureLogical Standby ArchitectureLogical Standby Architecture

.

ProductionPrimary

Database


LGWR

Logical DatabaseStandby Site

User EntersData

LogicalDatabase

Network

Logical StandbyProcess(LSP)

Transforms Redointo SQL

SQL Apply

User runsreports


Logical StandbyLogical StandbyLogical StandbyLogical Standby

• In event of disaster, logical standby can be

turned into a primary database• Can create indexes and MVs to tune it• Doesn’t support longs and raws

SQL> select * from dba_logstdby_unsupported;

• Many steps (20+) involved with setting up

logical standby• See MetaLink note: 186150.1


Data Guard BrokerData Guard BrokerData Guard BrokerData Guard Broker

• Two components– Command line tool– Data Guard Manager OEM GUI tool

• With Data Guard Manager, point and click your

way through setting up standby environment– Create physical and logical standby databases– Perform switchovers and failovers– Monitor log transport and apply– Configure event driven reporting/e-mailing/paging


Data Guard SummaryData Guard SummaryData Guard SummaryData Guard Summary

• Relies on tried-and-true standby technology• Ideal for disaster recovery and high availability• Fairly low cost• DBA needs to have backup and recovery skills

to create and maintain• Many new Data Guard features in Oracle9i• Now has some scalability features

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